TAXONOMY OF BACTERIA Instructor Terry Wiseth MICROBIOLOGY Northland Community & Technical College.
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Transcript of TAXONOMY OF BACTERIA Instructor Terry Wiseth MICROBIOLOGY Northland Community & Technical College.
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TAXONOMYTaxonomic classification based on:
gram staininggram positivegram negative
mode of respirationaerobic anaerobic
cell wall shapecoccibacillispiral
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TAXONOMYGram Positive BacilliGram Positive CocciGram Negative BacteriaSpirochetesRickettsiaChlamydia
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GRAM-POSITVE BACILLI
Clinically important genusAerobic
Bacillus Lactobacillus Listeria Erysipelothrix CorynebacteriumMycobacterium
AnaerobicClostridium Propionibacterium
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BACILLUSgenus of Gram-positive bacteriaubiquitous in nature (soil, water, and
airborne dust)Some species are natural flora in the
human intestines most species are harmless saprophytes two species are considered medically
significant B. anthracis B. cereus
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B. anthraciscauses anthrax in cows, sheep, and
sometimes humansAnthrax is transmitted to humans
via direct contact with animal products or inhalation of endospores
Anthrax can be treated with penicillin or tetracycline
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The anthrax bacteria can live in the soil for many years
Man may become infected with anthrax by inhaling contaminated soil particles or by handling wool or hair from diseased animals
Infection of the intestinal tract can occur by eating undercooked meat from diseased animals
B. anthracis
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B. cereus
can cause toxin-mediated food poisoning
It is known to inhabit many kinds of food including stew, cereal, and milk
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B. cereusThe toxins released lead to
vomiting and diarrheatoxin production usually takes
place after the infected foods are cookedproper cold storage of food is
recommended immediately after preparation
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LACTOBACILLUS ferment glucose into lactose
hence the name Lactobacillusmost common application of
Lactobacillus is industrialspecifically for dairy productionyogurt, sauerkraut, pickles,
buttermilk L. acidophilus
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make up part of the natural flora of the human vagina
create an acidic environment which inhibits growth of many bacterial speciesleads to urogenital infections
Lactobacillus is generally harmless to humans
LACTOBACILLUS
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Vegetables can become contaminated from the soil or from manure used as fertilizer
Animals can carry the bacterium without appearing ill and can contaminate foods of animal origin such as meats and dairy products
L. monocytogenes
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L. monocytogenes
has been implicated in several food poisoning epidemics (Listeriosis)
normal inhabitant of the gastrointestinal tract and of animal feces
infected suffer from vomiting, nausea, and diarrhea
those at high risk include newborns, pregnant women and their fetuses, the elderly, and persons lacking a healthy immune system
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ERYSIPELOTHRIXbetter known as a veterinary
pathogen than as a human pathogen
This ubiquitous microbe has been found in many farm animals such as pigs, horses, and turkeys
can infect a human host and cause Erysipeloid, an inflammatory skin disease
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CORYNEBACTERIUM
ubiquitous in naturenormally saprophytic and
harmless to humansexception is the bacterium C.
diphtheriaeproduces the toxin that causes
diphtheriaa disease of the upper respiratory
system in humansunique in its exotoxin formation
Alaskan Iditarod
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M. tuberculosis
Tubercle bacilli that reach the alveoli of the lung are ingested by macrophages but often survive
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M. tuberculosis
Tubercle bacilli multiplying in macrophages cause a chemotactic response that brings additional macrophages into the area, forming and early tubercle
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M. tuberculosis
After a few weeks many of the macrophages die, releasing tubercle bacilli and forming a caseous center in the tubercle, which is surrounded by a mass of macrophages and lymphocytes. The disease may become dormant after this stage.
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M. tuberculosis
In some individuals, a mature tubercle is then formed as a firm outer layer surrounds the mass of macrophages and lymphocytes. The caseous center enlarges in the process of liquefaction, forming and air-filled tuberculous cavity in which the bacilli multiply extracellularly
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M. tuberculosis
Liquefaction continues until the tubercle ruptures, allowing bacilli to spill into a bronchiole and thus be disseminated throughout the respiratory system and to other systems
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CLOSTRIDIUManaerobic, ubiquitous in nature, especially
fond of soil secrete powerful exotoxins that are
responsible fortetanusbotulismgas gangrene
clinically important species C. tetaniC. perfringensC. botulinum
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C. tetanicauses tetanus (lockjaw) in humansspores can be acquired from any
type of skin trauma involving an infected device
If an anaerobic environment is present, the spores will germinate and eventually form active C. tetani cells
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C. tetaniAt the tissue level, the bacterium
releases an exotoxin that causes nervous system irregularities
toxin's effect includes constant skeletal muscle contraction due to a blockage of inhibitory
interneurons that regulate muscle contraction
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C. tetani Immunization prevents C. tetani
infections in children and adultsthe first four shots are administered
within two years of birthfollowed up with periodic booster
shots given every ten years
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C. perfringenscan be contracted from dirt via
large cuts or woundsrelease of their exotoxin causes
necrosis of the surrounding tissue
also produce gas which leads to a bubbly deformation of the infected tissues (gas gangrene)
can release an enterotoxin that may lead to severe diarrhea
Gas Bubble
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C. botulinum
produces one of the most potent toxins in existence
cause of the deadly botulism food poisoningmay find their way into foods
that will be placed in anaerobic storage such as cans or jars
once the jars are sealed, the spores germinate and the bacteria release their potent toxin
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C. botulinum
patients experience muscular paralysis and blurred visionimmediate treatment with
anti-toxin is required for the patient to survive
infantile botulism is much milder than the adult versionhoney is the most common source of the
spores which germinate in the child's intestinal tract
symptoms last a few days and then subside without the use of an antitoxin
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PROPIONIBACTERIUM
anaerobes P. acnes
usually harmless microbe that has pathogenic potential
has been linked to certain cases of endocarditis, wound infections, and abscesses
Ironically, it can infect acne sites on the skin but it does not cause them
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GRAM-POSITIVE
COCCIclinically relevant gram-positive
cocci bacteriaMicrococcus Staphylococcus Streptococcus
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MICROCOCCUSobserved as spherical cells forming pairs
or clustersa common human skin contaminant
relatively harmless to humans because they maintain a saprophytic lifestyle
also found in freshwater environments or in soil
two common species are M. luteusM. varians
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S. aureuscan cause
soft tissue infectionstoxic shock syndrome (TSS)pneumoniameningitisboilsosteomyelitis (bone infection)
enterotoxins causes cramps and severe vomiting
also secretes leukocidintoxin which destroys WBC and leads to the formation of puss and acne
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S. epidermidisan opportunistic pathogen which is a
normal resident of human skin individuals susceptible to infection
IV drug usersnewbornselderlythose using
catheters or other artificial appliances
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STREPTOCOCCUSappear as chains
clinically significant genusS. pyogenesS. pneumoniaeS. agalactiaeS. mutans
produce exotoxins which destroyphagocytic cellshost connective tissuefibrin (blood clots)
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S. pyogenesan opportunistic pathogen is
responsible for about 90% of all cases of "Strep throat" characterized by inflammation and
swelling of the throat, as well as development of pus-filled regions on the tonsils
if the infection reaches the lungs it could lead to pneumonia or rheumatic fever
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S. agalactiae
the causative agent in mastitis in cows
has also been found to be a cause of sexually transmitted urogenital infections in females
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GRAM-NEGATIVE BACTERIA
Clinically significant genusNeisseriaHaemophilusBordetellaBrucellaFrancisella
PasteurellaLegionellaVibrioHelicobacterVibrioidsEnterobacteriaceae
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NEISSERIAdiplococci which inhabit the
mucous membranes clinically significant
N. gonorrhoeae N. meningitidis
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N. gonorrhoeae
Gonorrhea is transmitted between humans through intimate contact of the mucous membrane
can be carried by men and women for many years without any sign or symptoms
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The next picture is quite graphic
N. gonorrhoeae
Females infected with gonorrhea exhibit vaginal discharges, abdominal pain, and abnormal non-menstrual bleeding
In infected males, the disease is characterized by a urethral discharge of puss
this disease is treatablesensitive to ultraviolet
radiation, drying, and antibiotics
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Use of the birth control pill can lower the glycogen concentration of the vaginal membrane
This environmental change inhibits the growth of acid-producing bacteriasuch as Lactobacillus, which are the
natural flora of the vaginaThe vaginal pH soon becomes less
acidic and a variety of organisms are able to grow there
N. gonorrhoeae
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N. meningitidisthe second leading cause of
meningitisinflammation of the membranes
covering the central nervous system
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N. meningitidisEarly symptoms may include headache,
fever, and vomitingDeath can quickly follow due to
endotoxin shock Infection doesn't always lead
to deathcan often assume a carrier
status with carriers not actually developing the disease
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HAEMOPHILUScommon in children can cause a
secondary respiratory infection that usually inflicts those who already have the flu
H. influenzae occur as natural flora of the nose and pharynx
can confer severe illness in patients that are immunosuppressed or that have pre-existing respiratory ailments
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most common cause of bacterial meningitis in children between the ages of five months and five years
The initial respiratory infection can spread to the blood stream and eventually the central nervous system
A stiff neck, lethargy, and the absence of the sucking reflex are common symptoms in infected babies
HAEMOPHILUS
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H. influenzae is the number one cause of Epiglottitis
potentially fatal disease may cause airway obstruction in children between the ages of 2 and 4
HAEMOPHILUS
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Haemophilus infection has also been associated with chronic bronchitis, pneumonia, earaches, conjunctivitis and chancaroid (sexually transmitted)
HAEMOPHILUS
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BORDETELLAmost important species in this genus is B.
pertussiscauses whooping
coughhighly contagious
bacterium makes its way into the respiratory tract via inhalation subsequently binds to and destroys the
ciliated epithelial cells of the trachea and bronchi
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whooping cough usually afflicts children less than a year old
A vaccine has reduced the incidence of this disease one hundred fold since its introduction
BORDETELLA
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BRUCELLAcauses BrucellosisThis organism is sometimes carried by
animals and only causes incidental infections in humanscattle, swine, goats,
dogs Brucella can enter the
body via the skin, respiratory tract, or digestive tract
Symptoms can include high fever, chills, and sweating
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FRANCISELLAcauses tularemia
disease that humans can catch from tick bites
This highly infectious disease is carried by rodents, deer, pets, and many other animals
Humans can acquire the organism in several different ways through lesions in skin
A sudden onset of flu like symptoms (headache, fever, chills) is observed in infected individuals
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PASTEURELLAP. multocida is the species which
most commonly infects humanshumans can acquire the organism
from dog or cat bites
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PASTEURELLAPatients tend to exhibit swelling,
cellulitis, and some bloody drainage at the wound site
Infection may also move to nearby joints where it can cause swelling and arthritis
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LEGIONELLAfirst discovery of Legionella came in
1976outbreak of pneumonia at an
American Legion convention led to 29 deaths (Legionnaires' disease)
Respiratory transmission of this organism can lead to infection, which is usually characterized by a gradual onset of flu-like symptoms
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Patients may experience fever, chills, and a dry cough as part of the early symptoms
Patients can develop severe pneumonia which is not responsive to penicillins
LEGIONELLA
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VIBRIO
Vibrio species are non-invasive pathogenscan cause some of the most
serious cases of diarrhea and thousands of people die from infection annually
waterborne organisms are transmitted to humans via infected water or through fecal transmission
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Most clinically important is V. choleraein countries with poor sewage or water
treatment cholera is sometimes seen in epidemic proportions
characterized by severe diarrhea which has a rice-water color and consistency
The diarrhea is so severe that about 60% percent of cholera deaths are due to dehydration
VIBRIO
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After cholera organisms are ingested, they descend to the intestinal tract where they release their exotoxininduces the epithelial cells to
excrete saltThe cells then lose water which
passively flows out of the cellsFluid and electrolyte replacement is
the key to treating cholera patients
VIBRIO
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Intestinal lumen
NaCl
NaCl
NaCl
NaCl NaC
l
NaCl
NaCl
NaCl
NaCl
H2O
H2O
H2O H2O H2OH2O
H2OH2O H2O
H2O
H2O
BloodstreamPlasma ion levels drop
H2OH2O
H2OH2O
NaCl
NaCl
NaCl
NaCl
Plasma H2O levels drop (dehydration)
Vibrio invade the intestinal cells
Vibrio release enterotoxinsEnterotoxins cause intestinal cells to give up NaCl to the intestinal lumen
H2O follows NaCl by diffusion
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Another strain which causes diarrhea can be found in raw seafood such as sushi and oysters
VIBRIO
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HELICOBACTER leading cause of peptic ulcers and
chronic gastritis Infected patients can be treated
with an antacid as well as tetracycline to treat the ulcers and inhibit the growth of the organism
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VIBRIOIDSMost interesting is a bacterial
predatorslips in between the cell wall and
cell membrane of a host bacterium and parasitizes the organism
V. bdellovibrio
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ENTEROBACTERIACEAEamong the most pathogenic and
most often encountered organisms in clinical microbiology
large rods are usually associated with intestinal infections
can cause meningitis, dysentery, typhoid, and food poisoning
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Clinically importantEscherichia coliShigellaSalmonellaKlebsiellaProteusYersinia
ENTEROBACTERIACEAE
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ESCHERICHIA COLI
can cause urinary tract infections, pneumonia, meningitis, and traveler's diarrhea
part of the normal flora of the human intestinal tractplays a crucial role in food digestion
by producing vitamin K from undigested material in the large intestine
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ESCHERICHIA COLI
Pathogenic strains can cause severe cases of diarrhea in all age groups by producing a powerful endotoxin
Treating E. coli infections with antibiotics may actually place the patient in severe shock which could possibly lead to deathbecause more of the bacterium's
toxin is released when the cell dies
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SHIGELLA
In many cases Shigella infection will lead to diarrhea accompanied by fever
an invasive pathogen which can be recovered from the bloody stool of an infected hostInvasive pathogens colonize the host's
tissues as opposed to growing on tissue surfaces
is easily spread from host to hostthe primary suspect in outbreaks of
diarrhea
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SALMONELLACan cause bacterial food poisoning Transmission is usually through
uncooked meats and eggsChickens are a major reservoir of
Salmonellaexplains its ubiquitous
presence in poultry products
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Ingesting contaminated foods can cause intestinal infection leading to diarrhea, vomiting, chills, and headache
capsular properties can cause serious complications in immunosuppressed individuals such as HIV / AIDS patients
SALMONELLA
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S. typhosa causes typhoid fever (enteric fever) characterized by fever, diarrhea,
and inflammation of the infected organs
SALMONELLA
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KLEBSIELLAproduces large sticky colonies K. pneumoniae infections are common
in hospitals where they cause pneumonia and urinary tract infections in catheterized patients
cause of septicemia
Bacteria in biofilm on catheter
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PROTEUScan cause urinary tract
infections and hospital-acquired infections
usually only targets immunosuppressed individuals
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YERSINIA
an invasive pathogen which can penetrate the gut lining and enter the lymphatic system and the blood
ingestion of contaminated foods, can cause a severe intestinal inflammation called yersiniosis
Release of its enterotoxin can cause severe pain similar to that found in patients with appendicitis
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Y. pestis causes the bubonic, pneumonic, and septicemic plagues
Human contraction of bubonic plague is usually through flea bites
YERSINIA
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YERSINIAOnce inside the body, Y. pestis
releases a toxin which inhibits the Kreb’s cycle in host cells
Swelling of the lymph nodes, skin blotches, and delirium are sometimes observed within a few days of infection
Untreated infections usually result in death within a week of initial infection
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YERSINIAthe plague has historically been a
deadly pathogen inflicting Europeans in epidemic
proportions during the fourteenth, fifteenth, and sixteenth centuries
lack of sanitation allowed the plague to go unchecked killing tens of millions
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SPIROCHETES
Typically have a helical or spiral structure
clinically significant genusTreponemaBorelliaLeptospira
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BORELLIA
B.burgdorferi is the agent which causes Lyme Disease
typically spread by bites of small ticks
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LEPTOSPIRAmembers of this
genus can cause leptospirosis
spread by contaminated urine from pets
pets are commonly immunized
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RICKETTSIAcan reproduce only within a host
cellR. ricketsii is cause of Rocky
Mountain Spotted Fever which is carried in the digestive tract of some species of ticks
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CHLAMYDIA
do not require insects or ticks for transmission
C. trachomais is a sexually transmitted urethritis